Buggy code:
public class Data { private static ArrayList < User > users ; private static Hashtable < User , MetaSheet > meta ; private static DayTable defaultConfiguration ; private static boolean editEnabled ; private static File file ; @ XmlRootElement ( name = "database" ) private static class Loader { private DayTable dc ; private boolean editEnabled ; private String lastVersion ; private ArrayList < User > user ; private Hashtable < User , MetaSheet > meta ; public ArrayList < User > getUsers ( ) { } public void setUsers ( ArrayList < User > users ) { } public Loader ( ) { } public DayTable getDefaultConfiguration ( ) { } public void setDefaultConfiguration ( DayTable defaultConfiguration ) { } public boolean isEditEnabled ( ) { } public void setEditEnabled ( boolean editEnabled ) { } public String getLastVersion ( ) { } public void setLastVersion ( String lastVersion ) { } public Hashtable < User , MetaSheet > getMeta ( ) { } public void setMeta ( Hashtable < User , MetaSheet > meta ) { } } @ XmlRootElement ( name = "database" ) private static class OldLoader { private DayTable dc ; private boolean editEnabled ; @ SuppressWarnings ( "unused" ) private String lastVersion ; private ArrayList < User > user ; public ArrayList < User > getUsers ( ) { } public DayTable getDefaultConfiguration ( ) { } public boolean isEditEnabled ( ) { } } public static DayTable getDefaultConfiguration ( ) { } public static void setDefaultConfiguration ( DayTable defaultConfiguration ) { } public static boolean isEditEnabled ( ) { } public static void setEditEnabled ( boolean editEnabled ) { } public static boolean save ( ) { } public static User getUser ( String userName ) { } public static User getUser ( int ID ) { } public static boolean addUser ( User u ) { } public static int getLatestID ( ) { } public static int [ ] getAllIDs ( ) { } public static final void loadDataFile ( String file ) { } public static final void loadOldDataFile ( String file ) { } public static int getUserCount ( ) { } public static void checkDatabase ( ) { } private static void repairDatabase ( ) { Console . log ( Warning , "Database" , "Some<seq2seq4repair_space>corrupted<seq2seq4repair_space>data<seq2seq4repair_space>was<seq2seq4repair_space>found.<seq2seq4repair_space>The<seq2seq4repair_space>system<seq2seq4repair_space>now<seq2seq4repair_space>trys<seq2seq4repair_space>to<seq2seq4repair_space>correct<seq2seq4repair_space>it." ) ; for ( User u : Data . users ) { <START_BUG> if ( ! ( Data . meta . contains ( u ) ) ) { <END_BUG> Console . log ( Information , "Database" , ( "Adding<seq2seq4repair_space>missing<seq2seq4repair_space>meta<seq2seq4repair_space>data<seq2seq4repair_space>for<seq2seq4repair_space>user<seq2seq4repair_space>" + ( u . getName ( ) ) ) ) ; MetaSheet s = new MetaSheet ( u . getID ( ) ) ; MetaReg . setDefaultMetaData ( s ) ; Data . meta . put ( u , s ) ; } else { Console . log ( Information , "Database" , ( "Rerouting<seq2seq4repair_space>incorrect<seq2seq4repair_space>placed<seq2seq4repair_space>data<seq2seq4repair_space>of<seq2seq4repair_space>" + ( u . getName ( ) ) ) ) ; MetaSheet s = Data . meta . get ( u ) ; if ( ( u . getID ( ) ) != ( s . getAssoziatedUser ( ) ) ) { Data . meta . remove ( u ) ; Data . meta . put ( Data . getUser ( s . getAssoziatedUser ( ) ) , s ) ; } } } } public static int setEntry ( User target , String key , String value ) { } public static String getEntry ( User target , String key ) { } private static void postInit ( ) { } }

Fix:
if ( ! ( Data . meta . containsKey ( u ) ) ) {